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Subnetting

How I learned subnetting (back from ~2009)

HOW TO DETERMINE THE AMOUNT OF HOSTS PER SUBMIT AND SUBMIT - 172.16.0.0/23

  • WRITE THE MASK IN BINARY: /23 = 11111111.11111111.11111110.00000000
  • REMOVE THE NETWORK BITS FROM THE MASK.
    • SINCE THIS IS A CLASS B NETWORK, REMOVE THE FIRST 16 BITS.
    • 11111110.000000000
  • COUNT THE NUMBER OF 1'S
    • TAKE THAT NUMBER CALCULATE TO THE 2^N WHERE N = 1'S
    • 2^7 = 128 SUBNETS
  • COUNT THE NUMBER OF 0'S
    • TAKE THAT NUMBER CALCULATE TO THE (2^N)-2 WHERE N = 0'S
    • (2^9=512)-2 = 510

Answer

  • SUBNETS = 128
  • HOSTS PER SUBNET = 510

For more practice, use this site: https://subnettingpractice.com/